U.S. Pat. No. 3,976,348 (U.S. Reissue Pat. No. 30277) discloses a stamped and formed electrical terminal receptacle which is dimensioned to receive a terminal tab having a rectangular cross section. The receptacle terminal is of the type having a web and having sidewalls which extend from the marginal side portions of the web and which are formed inwardly towards each other and towards the web so that a terminal tab can be inserted between the surface of the web and the free edge portions of the sidewalls. Terminals of this general type are widely used for the reason that they can be mated with standard terminal tabs having a rectangular cross section. The terminal receptable described in U.S. Pat. No. 3,976,348 has a tongue extending from the web at the tab receiving end of the receptacle. The tongue is reversely bent at the tab receiving end and has an intermediate portion which engages an inserted tab. The free end of the tongue extends beyond the receptacle section or portion of the terminal and is engageable so that it can be flexed towards the web. The intermediate portion of the tongue has a locking lance which is received in an opening in the tab which locks the tab to the terminal receptacle upon insertion. The tab can be disengaged by simply flexing the tongue towards the web portion of the terminal.
Terminal receptacles having locking feature in U.S. Pat. No. 3,976,348 are being used to an increasing extent on a variety of types of electrical equipment. The provision shows locking feature, which prevents disengagement of the receptacle from an inserted tab, is highly desirable for reasons of improved reliability and safety. Terminal receptacles which are used under circumstances where unauthorized tampering may be a problem can be provided with the locking feature of the above identified U.S. Patent to eliminate problems with unauthorized or mischievous meddling.
The present invention is directed to an improved terminal receptacle having a locking feature which can be produced with substantially less material than the terminal shown in U.S. Pat. No. 3,976,348 and which can be designed to provide a contact force within a broad range at the electrical interface between the terminal receptacle and a tab with which is it mated.
A preferred embodiment of the invention comprises a stamped and formed receptacle terminal having a receptacle portion which is dimensioned to receive a tab-type terminal, the receptacle portion having a web and having sidewalls extending from the marginal side portions of the web. The sidewalls are formed inwardly of the web and towards each other and have free edges which are spaced from the surface of the web. The receptacle portion has a tab-receiving end and an inner end, whereby upon relative movement of the tab into the tab-receiving end towards the inner end, electrical contact is established between the tab and the receptacle portion. The receptacle portion has a releasable latch for releasably latching the tab to the receptacle portion. A receptacle terminal in accordance with the invention is partially characterized in that the releasable latch comprises a latching tongue struck from the web of the receptacle portion, the web having an opening therein which is also produced when the tongue was struck from the web. The tongue has a fixed end and a free end and has side edges extending between the ends and alongside the marginal side portions of the web. The fixed end is proximate to one of the ends of the receptacle portion and the free end is proximate to the other end of the receptacle portion. The tongue has an intermediate portion which extends from the fixed end to a location proximate to the free end and has an engaging ear extending from the intermediate portion to the free end. The engaging ear extends obliquely away from the free edges of the sidewalls and through the opening in the web whereby the free end of the tongue can be engaged and manipulated. Latching portions or latching means are provided on the intermediate portion of the tongue and are engageable with complimentary latching portions on a terminal tab when the tab is inserted into the receptacle portion. The tongue can be disengaged from the tab by engaging the engaging portion of the tongue and flexing the tongue away from the free edges of the sidewalls until the latching portions of the tongue are disengaged from the complimentary latching portions of the tab.
In accordance with a further embodiment, the intermediate portion of the tongue extends from the fixed end obliquely, with respect to the plane of the web, towards the free edges of the sidewalls. In accordance with a further embodiment, the free end of the tongue is proximate to the tab-receiving end of the receptacle portion. In accordance with a further embodiment, the fixed end of the tongue is proximate to the inner end of receptacle portion. In accordance with a further embodiment, the web has stop portions which are proximate to the side edges of a tongue and which extend beneath the tongue, and beyond the side edges of the opening in the web thereby to prevent overstressing of the tongue during flexure. In accordance with a further embodiment, the stop portions comprise ears which are produced by severing the web along severing lines that extend transversely from the associated edge of the opening in the web, the ears being subsequently coined so that they project beyond the side edges of the opening. In accordance with a further embodiment, an insulating housing is provided in surrounding relationship to the terminal and is axially movable relative to the terminal. The housing has a shoulder which engages the engaging portion of the tongue during relative movement to flex the tongue and disengage the tab from the receptacle portion.